Figure 4.

Magnitude of transmitter release in neurons expressing synaptotagmin I mutants. Peak amplitude of EPSCs (A) and cumulative amount of charge released (B) from knock-out neurons expressing either wild-type (Stg I) or mutated (D1N-D5N) synaptotagmin I. Total charge transfer was measured over 400 msec after the stimulus. Values are means ± SEM (Stg I, n = 11; D1N, n = 8; D2N, n = 5; D3N, n = 5; D4N, n = 6; D5N, n = 7). Asterisks indicate values that are significantly different (p < 0.05) from those obtained from cells transfected with wild-type synaptotagmin I.